Problem: Evaluate the following expression when $c = 4$ and $d = 5$. $9$ $c$ $ + 4$ $d$ $ + 10$
Answer: Substitute $4$ for ${c}$ and $5$ for ${d}$ $ = 9{(4)} + 4{(5)} + 10 $ $ = 36 + 20 + 10 $ $ = 66$